A so-called tilt box is used to guide a continuously moving web in a printing operation, although it is possible to use such devices also in the textile field. Such a guide apparatus or tilt box eliminates so-called sidelay error which occurs in printing when a splice is improperly made between succeeding paper webs, or when the web being fed is not perfectly flat. The purpose of such a machine is to insure that any sidelay error upstream is eliminated downstream.
The standard such device includes a frame carrying a pair of adjustment rollers. The web is passed in a nonstraight path over these adjustment rollers so as to engage both of them over a substantial arc. This frame can be pivoted about an axis perpendicular to that of the web. In this manner pivoting of the frame so that the axes of its rollers do not lie perfectly perpendicular to the direction of travel of the paper over them will laterally displace the web. Sensors are normally provided somewhat downstream of the apparatus that controls the motor that pivots the frame so as automatically to eliminate any sidelay error appearing downstream.
Typically such apparatuses, as seen in U.S. Pat. No. 3,615,048, have a relatively open construction or frame. The motor as well as the various control and sensing devices are provided normally immediately adjacent the adjustment rollers. Frequently the sensors are connected via loose wires to the motor.
The disadvantages of this type of system is that it is normally functioning in an extremely dusty environment. Thus all of these parts quickly become covered with dust, creating considerable danger of malfunctioning due to all this dust in the mechanism. Another disadvantage is that such a system is relatively dangerous to work near, as the exposed mechanism and electrical or pneumatic lines can be hazardous.